Liber de Causis (The Book of Causes)

1245. Even before him at Oxford, where the Parisian prohibitions did not apply, the Liber de causis was taught by Alexander Neckham, Adam of Buckfield, and Thomas of York. Its official ratification as a fundamental source for philosophical studies, however, occurred on March 19, 1255, when it became a required text at the Faculty of Arts in Paris according to new statutes. From this date, every professor was required to devote seven weeks to the reading and